with open("re.txt", "r", encoding='utf-8') as readfile, open("messages copy.properties", "r+", encoding='utf-8') as writefile:
    lines_readfile = readfile.readlines()
    lines_writefile = writefile.readlines()
    for i in range(len(lines_readfile)):
        lines_writefile[i] = lines_writefile[i].strip() + lines_readfile[i]
    writefile.seek(0)
    writefile.writelines(lines_writefile)
